Abstract: Aimed at the situation of severe corrosion on the casings in the water source well JX1-1-A1w, the authors analyzed the affecting factors on the corrosion and probed into the mechanism of scaling in the wellbore based on the analysis of water, gas, downhole scale samples and laboratory test. The results show that bacteria corrosion and scaling corrosion induced by sulfate reducing bacteria (SRB) are the predominating reason. There are a large amount of ferrous sulfide in the corrosion scaling and easily produce hydrogen sulfide when the acid is used to descaling. The results suggest a preliminary solution to the production, descaling, perforating in the similar well in future.